Append Single File to Existing Zip

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Delphi example code to open a Zip archive, append a single file, and rewrite the .zip.

// Opens an existing .zip and append a single file to it.
procedure TForm1.Button5Click(Sender: TObject);
var
  saveExtraPath: Integer;
  success: Integer;
begin
  ChilkatZip21.UnlockComponent('anything for 30-day trial');

  // Open an existing .zip file.
  success := ChilkatZip21.OpenZip('test.zip');
  if (success = 0) then
    begin
      ChilkatZip21.SaveLastError('zipErrorLog.txt');
      ShowMessage(ChilkatZip21.LastErrorText);
    end
  else
    begin
      saveExtraPath := 0;   // Do not save the full path.

      // After calling WriteZip, test.zip will contain the entry "hamlet.xml" with
      // no directory path.
      ChilkatZip21.AppendOneFileOrDir('c:\temp\myApp\hamlet.xml', saveExtraPath);

      // Re-write the .zip
      // Note: The .zip file format is such that it is not possible to incrementally
      // add files to the .zip without completely re-writing the entire .zip.
      ChilkatZip21.WriteZip();

      // Alternative ways of appending a single file:

      // The .zip will contain "temp\myApp\hamlet.xml" by using this code:
      saveExtraPath := 1;
      ChilkatZip21.AppendOneFileOrDir('c:\temp\myApp\hamlet.xml', saveExtraPath);

      // The .zip will contain "myApp\hamlet.xml" by using this code:
      saveExtraPath := 1;
      ChilkatZip21.AppendFromDir := 'c:\temp\';   // Relative paths are evaluated from this base path
      ChilkatZip21.AppendOneFileOrDir('myApp\hamlet.xml', saveExtraPath);

      // Re-write the .zip
      ChilkatZip21.WriteZip();

    end;